John bought 3 shirts and 4 pairs of socks for $78.
Joan bought 2 shirts and 6 pairs of socks for $72.

Letting $x equal the price of a shirt and $y equal the price of a pair of socks, write a linear equation to represent each transaction.
Draw on the same axes the graphs of the two equations. Read off the co-ordinates of the point of intersection to find the values of x and y.